1. Field of the Invention
The present invention relates to a sound field compensating apparatus for producing a simulating reflected sound signal corresponding to a direct sound signal.
2. Description of the Related Art
There has been well known a sound field compensating apparatus for executing signal processes for a sound field control to audio signals so as to give presence in a home or vehicle by producing a sound field which is obtained by simulating the sound field in an acoustic space of a concert hall or a theater. Such a sound field compensating apparatus has a digital signal processor (abbreviated to DSP) which performs arithmetic processing of digital signals supplied from an audio signal source such as a tuner or the like. The DSP comprises a calculation section for performing arithmetic operation, e.g. multiplication, division, addition, and subtraction, and a storage section consisted mainly of a data memory for storage of digital audio signal data which are to be delivered to the calculation section, a coefficient memory for storage of coefficient data which is multiplied by the factor of the audio signal data, and other memories Also, it is provided with an external delay memory for delaying the signal data and a delay time memory for storage of delay time data which carry information of a duration from writing to reading of the signal data on the delay memory. In the operation of the DSP, the signal data are processed at high speeds through transfer of relevant data between the memories and from the memories to the calculation section in accordance with a processing program. For example, a signal data supplied by sampling is fed to the delay memory where it is delayed and shifted to a delay signal data. The delay signal data is then transferred via the data memory to the calculation selection where it is multiplied by the factor of a coefficient data to produce a simulating reflected sound data for compensation for sound level attenuation. In response to supply of one sampling signal data, a plurality of reflected sound data which are different in the delay time and the coefficient value are produced and added to an original sound data or input signal data as a direct sound data. A resultant signal adding both the input sound data and the reflected sound data is then output from the DSP and converted to an analog signal for driving a speaker.
However, the conventional sound field compensating apparatus employing a DSP contains a delay element for each channel thus limiting the number of delay data which are retrieved from the delay memory during one sampling period. As the result, if a multiplicity of channels are used, the reflected sound data will no more be increased.